Evidence of the plumes is visible in recent observations made by the Hubble Space Telescope, William Sparks, an astronomer with the Space Telescope Science Institute in Baltimore, said in the briefing. The new report confirms similar observations that were made in 2013.

The plumes provide additional evidence that beneath Europa’s icy surface lies a vast underground ocean of liquid water. In addition, they suggest that it might be easier than some had thought to search for signs of life on the moon, which has long been considered one of the likeliest places to find extraterrestrial life in the solar system.

“If there are plumes emerging from Europa, it’s significant because it means we may be able to explore that ocean of Europa for organic chemicals or even signs of life without having to drill through unknown miles of ice,” Sparks said.

Here’s an artist’s illustration of water vapor plumes erupting from Europa’s surface:

Scientists estimate the plumes rise about 125 miles from Europa’s surface before raining back down. If there’s life in the subsurface ocean, it could be brought to the surface by the water jets, becoming visible to a visiting spacecraft.

“Who could ask for more?” Seth Shostak, senior astronomer at the SETI Institute and a noted expert on the search for extraterrestrial life, said in an email to The Huffington Post. “Europa, one of the choice locations in the solar system for biology, is possibly offering it up to us on a platter. Rather than sending a lander and a drilling rig capable of making a 10-mile hole in granite-hard ice, all we may have to do is send an orbiter around this intriguing moon, outfitted with a catcher’s mitt. We grab some of that plume, bring it back to Earth, and look for evidence of alien microbes in the comfort of our labs.”

The live-streamed announcement capped days of intense speculation over just what NASA would reveal at the briefing.

Some had wondered if the space agency might announce that alien life had been found. But in the hours leading up to the briefing, NASA threw cold water on that idea, saying “Spoiler alert: NOT aliens” in a pair of blunt tweets, including this one: